Posted: 12/14/2011 6:21:08 PM EDT
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I am assuming that not all AWD systems are created equal, but I have no idea what distinguishes one manufacturer's set up from another's. I know the systems from Audi and Subaru seem to have cult followings whereas the systems from companies like Ford and Honda are just kind of there. That said, I'd like to "open the floor" to those in the know. School us.
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Quoted:
I am assuming that not all AWD systems are created equal, but I have no idea what distinguishes one manufacturer's set up from another's. I know the systems from Audi and Subaru seem to have cult followings whereas the systems from companies like Ford and Honda are just kind of there. That said, I'd like to "open the floor" to those in the know. School us. GM Safari mini van with all wheel drive. Engineers put it on a vehicle with a 502 hp 502 crate engine and abused it for 3-4 months. Nothing broke. Result was the 345 hp C3 pickup. All of them are probobly less problematic than a 4wd system as far as maintaining them and being problem free over the life of the vehicle. |
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IIRC...Subarus AWD systems are symmetrical, meaning half of the power goes to the front and half goes to the back..
Audis I think is variable...I just wiki'd it, it says the newest generation can have up to 70 percent of the power up front and up to 85 percent in the back based on the conditions.. Pretty sure Ford/Lincolns is front wheel biased, with something like 70 up front and 30 in the rear.. Thats about where my knowledge on the subject stops lol |
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Quoted: I am assuming that not all AWD systems are created equal, but I have no idea what distinguishes one manufacturer's set up from another's. I know the systems from Audi and Subaru seem to have cult followings whereas the systems from companies like Ford and Honda are just kind of there. That said, I'd like to "open the floor" to those in the know. School us. Most AWD systems are fake wheel drive with open front and open rear differentials. Some have viscous coupling center differentials like the WRX, while others have mechanical center differentials like the STI and I believe most Audi's. There are only a handful of AWD vehicles with limited slip front, rear, AND center differentials: Lancer EVO, STI, and Lamborghini Murcielago. Some AWD vehicles are more sporty with a limited slip rear differential, like the Mazda CX-7, Acura, etc... Most AWD vehicles have a front-wheel bias like Ford, and use open front and rear differentials, so they're not very sporty - like the Ford system. This also exhibits severe understeer, like the Taurus SHO Egoboost and MKS EgoBoost. They rely on electronic assist like traction control and stability control, which aren't as good as the mechanical LSD units. I checked into installing a LSD front diff on a WRX and it was cost and time intensive but feasible. Audi started with a rear-wheel bias with the 2007 S5, which helps reduce the understeer. You will still want good tires and enough ground clearance for deep snow. Summer tires on a STI or Lancer Evo will result in you getting stuck in deep snow with all 4 tires spinning. |
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I am assuming that not all AWD systems are created equal, but I have no idea what distinguishes one manufacturer's set up from another's. I know the systems from Audi and Subaru seem to have cult followings whereas the systems from companies like Ford and Honda are just kind of there. That said, I'd like to "open the floor" to those in the know. School us. Most AWD systems are fake wheel drive with open front and open rear differentials. Some have viscous coupling center differentials like the WRX, while others have mechanical center differentials like the STI and I believe most Audi's. There are only a handful of AWD vehicles with limited slip front, rear, AND center differentials: Lancer EVO, STI, and Lamborghini Murcielago. Some AWD vehicles are more sporty with a limited slip rear differential, like the Mazda CX-7, Acura, etc... Most AWD vehicles have a front-wheel bias like Ford, and use open front and rear differentials, so they're not very sporty - like the Ford system. This also exhibits severe understeer, like the Taurus SHO Egoboost and MKS EgoBoost. They rely on electronic assist like traction control and stability control, which aren't as good as the mechanical LSD units. I checked into installing a LSD front diff on a WRX and it was cost and time intensive but feasible. Audi started with a rear-wheel bias with the 2007 S5, which helps reduce the understeer. You will still want good tires and enough ground clearance for deep snow. Summer tires on a STI or Lancer Evo will result in you getting stuck in deep snow with all 4 tires spinning. On the other hand, when you are talking about the snow-worthy AWDs in comparison to the 4wds, most of the 4wds out there are also "fake wheel drive" and suffer from greatly differing driving characteristics when driven in 4wd. When it comes to handling and driveability on paved roads covered in up to 10-12" of snow/slush/sleet/crap, both our Subarus and Rav4s dramatically outperform my full-sized GMC truck (which does have an LSD) and all the 4wd trucks and Bronco's I have owned in the past 30 years. Given equally good true extreme snow tires, I think the Outback might have a small edge in snow driving over our Rav, but tire life is almost triple on the Rav compared to the Subby. When it comes to real deep stuff, mud, and real off-road work/play, the 4wds do shine though. |
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Quoted: Quoted: Quoted: I am assuming that not all AWD systems are created equal, but I have no idea what distinguishes one manufacturer's set up from another's. I know the systems from Audi and Subaru seem to have cult followings whereas the systems from companies like Ford and Honda are just kind of there. That said, I'd like to "open the floor" to those in the know. School us. Most AWD systems are fake wheel drive with open front and open rear differentials. Some have viscous coupling center differentials like the WRX, while others have mechanical center differentials like the STI and I believe most Audi's. There are only a handful of AWD vehicles with limited slip front, rear, AND center differentials: Lancer EVO, STI, and Lamborghini Murcielago. Some AWD vehicles are more sporty with a limited slip rear differential, like the Mazda CX-7, Acura, etc... Most AWD vehicles have a front-wheel bias like Ford, and use open front and rear differentials, so they're not very sporty - like the Ford system. This also exhibits severe understeer, like the Taurus SHO Egoboost and MKS EgoBoost. They rely on electronic assist like traction control and stability control, which aren't as good as the mechanical LSD units. I checked into installing a LSD front diff on a WRX and it was cost and time intensive but feasible. Audi started with a rear-wheel bias with the 2007 S5, which helps reduce the understeer. You will still want good tires and enough ground clearance for deep snow. Summer tires on a STI or Lancer Evo will result in you getting stuck in deep snow with all 4 tires spinning. On the other hand, when you are talking about the snow-worthy AWDs in comparison to the 4wds, most of the 4wds out there are also "fake wheel drive" and suffer from greatly differing driving characteristics when driven in 4wd. When it comes to handling and driveability on paved roads covered in up to 10-12" of snow/slush/sleet/crap, both our Subarus and Rav4s dramatically outperform my full-sized GMC truck (which does have an LSD) and all the 4wd trucks and Bronco's I have owned in the past 30 years. Given equally good true extreme snow tires, I think the Outback might have a small edge in snow driving over our Rav, but tire life is almost triple on the Rav compared to the Subby. When it comes to real deep stuff, mud, and real off-road work/play, the 4wds do shine though. You can't compare 4WD with AWD, unless you're talking about a full-time 4WD system with a torque biasing center differential, like the HMMWV/H1 which BTW does have limited slip/Torsen front and rear differentials. It's not the ultimate off-roading vehicle, but it's very good. But yes, I'd consider some of those 4WD vehicles to be fake-wheel drive especially with an open rear differential! I can live with an open front differential, unless you're hitting the race tracks and need cornering speed. The F-150 Raptor has an electronically locking rear differential (up to 100 MPH in 2WD mode) and an open front differential (I believe they're changing it for 2012??), while the FX4 is supposed to only allow the E-locker to function in 4WD mode up to a certain speed. This compromises dry/wet performance and focuses more on desert racing or snow/mud. With a part-time 4WD, you're in 2WD (RWD) until you hit the slippery stuff. You're not supposed to drive in 4WD on dry tarmac, as an example. With AWD, you can drive on mixed surfaces. I have yet to find a vehicle with an open rear differential that had better traction than a vehicle with a limited slip rear differential - assuming the same conditions and same tires. The more power that gets sent to the front wheels on a typical SUV/pickup, the more you will feel plowing or perceived understeer which is the opposite of a good handling vehicle. Again, ground clearance and tires are very important for the deeper snow. Taking off in deep snow shows how AWD/4WD can be better than FWD/RWD, but once you have enough momentum it isn't as noticeable. |
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Some systems use open front, rear and center differentials and apply the brakes on a spinning wheel to transfer power to the non spinning wheel. This setup can be had with a two speed transfer case as well, and also with locking center, rear, and even front differentials depending on the model and options.
Some transfer cases use a clutch type center differential, some a viscous coupling, and some a mechanical style (planetary gearset). Some transfer cases have exotic fluid requirements, flat towing restrictions, and varying abilities of power handling, locking characteristics and user controls. Some AWD systems adapt a primarily FWD vehicle to AWD, other adapt a RWD vehicle to AWD, and even others adapt a 4WD vehicle to AWD. Personally, I tend to think of an AWD vehicle as one that is permanently AWD, as in it cannot be driven in a 2wd mode. Virtually any mix of all or four wheel drive systems has been used in production at some point. Some are used simply for their lower cost or compact configurations. |
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I am assuming that not all AWD systems are created equal, but I have no idea what distinguishes one manufacturer's set up from another's. I know the systems from Audi and Subaru seem to have cult followings whereas the systems from companies like Ford and Honda are just kind of there. That said, I'd like to "open the floor" to those in the know. School us. Most AWD systems are fake wheel drive with open front and open rear differentials. Some have viscous coupling center differentials like the WRX, while others have mechanical center differentials like the STI and I believe most Audi's. There are only a handful of AWD vehicles with limited slip front, rear, AND center differentials: Lancer EVO, STI, and Lamborghini Murcielago. Some AWD vehicles are more sporty with a limited slip rear differential, like the Mazda CX-7, Acura, etc... Most AWD vehicles have a front-wheel bias like Ford, and use open front and rear differentials, so they're not very sporty - like the Ford system. This also exhibits severe understeer, like the Taurus SHO Egoboost and MKS EgoBoost. They rely on electronic assist like traction control and stability control, which aren't as good as the mechanical LSD units. I checked into installing a LSD front diff on a WRX and it was cost and time intensive but feasible. Audi started with a rear-wheel bias with the 2007 S5, which helps reduce the understeer. You will still want good tires and enough ground clearance for deep snow. Summer tires on a STI or Lancer Evo will result in you getting stuck in deep snow with all 4 tires spinning. On the other hand, when you are talking about the snow-worthy AWDs in comparison to the 4wds, most of the 4wds out there are also "fake wheel drive" and suffer from greatly differing driving characteristics when driven in 4wd. When it comes to handling and driveability on paved roads covered in up to 10-12" of snow/slush/sleet/crap, both our Subarus and Rav4s dramatically outperform my full-sized GMC truck (which does have an LSD) and all the 4wd trucks and Bronco's I have owned in the past 30 years. Given equally good true extreme snow tires, I think the Outback might have a small edge in snow driving over our Rav, but tire life is almost triple on the Rav compared to the Subby. When it comes to real deep stuff, mud, and real off-road work/play, the 4wds do shine though. You can't compare 4WD with AWD, unless you're talking about a full-time 4WD system with a torque biasing center differential, like the HMMWV/H1 which BTW does have limited slip/Torsen front and rear differentials. It's not the ultimate off-roading vehicle, but it's very good. But yes, I'd consider some of those 4WD vehicles to be fake-wheel drive especially with an open rear differential! I can live with an open front differential, unless you're hitting the race tracks and need cornering speed. The F-150 Raptor has an electronically locking rear differential (up to 100 MPH in 2WD mode) and an open front differential (I believe they're changing it for 2012??), while the FX4 is supposed to only allow the E-locker to function in 4WD mode up to a certain speed. This compromises dry/wet performance and focuses more on desert racing or snow/mud. With a part-time 4WD, you're in 2WD (RWD) until you hit the slippery stuff. You're not supposed to drive in 4WD on dry tarmac, as an example. With AWD, you can drive on mixed surfaces. I have yet to find a vehicle with an open rear differential that had better traction than a vehicle with a limited slip rear differential - assuming the same conditions and same tires. The more power that gets sent to the front wheels on a typical SUV/pickup, the more you will feel plowing or perceived understeer which is the opposite of a good handling vehicle. Again, ground clearance and tires are very important for the deeper snow. Taking off in deep snow shows how AWD/4WD can be better than FWD/RWD, but once you have enough momentum it isn't as noticeable. All 2012 Raptors have a Torsen front differential and a "100 MPH" rear e-locker as standard equipment. My 2012 Raptor is supposed to be built on Monday and delivered on 1/02/12. I can't wait to pick it up. IMHO, the Raptor's rear locker and front Torsen is the ideal set-up for my use. |
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Quoted:
I am assuming that not all AWD systems are created equal, but I have no idea what distinguishes one manufacturer's set up from another's. I know the systems from Audi and Subaru seem to have cult followings whereas the systems from companies like Ford and Honda are just kind of there. That said, I'd like to "open the floor" to those in the know. School us. Most Subaru dealers I've been to have a display and scale models showing the differences in various AWD systems. I thought it was pretty informative. We just bought Mrs. matt33 a 2012 Subaru Legacy, it seems outstanding in the snow and handles pretty good too. So far, we're very happy with the Subaru. My company car is a 2011 Jeep Patriot; I am far less impressed with the Patriot than I am with the Legacy. |